DPS 2001 meeting, November 2001
Session 50. Solar System Dust
Oral, Chair: F. Spahn, Friday, November 30, 2001, 5:50-6:40pm, Regency GH

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[50.05] Dust from the Outer Jovian Satellites

A.V. Krivov (U. Potsdam), I. Wardinski (GFZ Potsdam), F. Spahn (U. Potsdam), H. Krüger, E. Grün (MPI-K, Heidelberg)

It is argued that the outer region of the jovian system between ~50 and 300 jovian radii from Jupiter harbors a previously unknown dust population. We analyzed the data of the dust detector aboard the Galileo spacecraft collected from December 1995 to April 2001 during Galileo's numerous traverses of the outer jovian system. About 100 individual events are found to be compatible with impacts of grains moving around Jupiter in bound orbits. These micrometer-sized grains have moderate eccentricities and a wide range of inclinations -- from prograde to retrograde ones. The radial profile of the dust number density is nearly flat between about 50 and 300 jovian radii, and the absolute number density level (~10km-3) surpasses by a factor of ten that of the interplanetary background. We identify the sources of the bound grains with outer irregular satellites of Jupiter. Six tiny moons orbiting the planet in prograde and fourteen in retrograde orbits should produce dust through continuous bombardment by interplanetary micrometeoroids. Our analytic and numerical study of the ejecta dynamics shows that micrometer-sized particles from both satellite families, although strongly perturbed by solar tidal gravity and radiation pressure, would stay in bound orbits for hundreds of thousands of years. The ejecta cloud would embrace the orbits of the parent moons and have substantial asymmetries created by the radiation pressure and solar gravity perturbations. Spatial location of the impacts, grains' orbital inclinations, mass distribution, speeds, and number density of dust derived from the data are all consistent with the dynamical model.

This work was funded by Deutsches Zentrum für Luft- und Raumfahrt (DLR).

The author(s) of this abstract have provided an email address for comments about the abstract: krivov@agnld.uni-potsdam.de

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